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A Leading Order QCD Computation of ππ Elastic Scattering


Kanwal, Sarbmeet Singh (1983) A Leading Order QCD Computation of ππ Elastic Scattering. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/7xbf-c510.


This thesis presents the results of a detailed computation of the leading order scattering amplitude and cross-section for the elastic reaction π+π+ → π+π+, in the context of the quark model and perturbative QCD. The calculation is based on the recently demonstrated applicability of QCD-factorization and the renormalization group to exclusive hadronic processes at large momentum-transfers. We show that a large fraction of the hard subprocess diagrams have a pinch singularity in them, which means that the amplitude resulting from these diagrams cannot be proved to be short-distance dominated. This contribution to the scattering amplitude is computed separately and, even after including a Sudakov factor, it is shown to be comparable in magnitude to the hard-scattering contribution. We calculate the energy and angular dependence of the pinch contribution and point out that some of the systematic deviations from power-law scaling, observed in high-PT meson-baryon and baryon-baryon elastic scattering data, can be explained by assuming that the cross-section for these reactions is dominated by pinch, rather than hard, effects. By normalizing the pion distribution amplitude with the help of the pion decay constant, we have also determined the absolute normalization of the ππ elastic cross-section.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Physics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Fox, Geoffrey C.
Thesis Committee:
  • Fox, Geoffrey C. (chair)
  • Feynman, Richard Phillips
  • Frautschi, Steven C.
  • Barish, Barry C.
  • McKeown, Robert D.
Defense Date:2 November 1982
Funding AgencyGrant Number
Record Number:CaltechTHESIS:10172019-165231405
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11824
Deposited By: Mel Ray
Deposited On:18 Oct 2019 00:08
Last Modified:16 Apr 2021 22:20

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